In recent years, there have been advances in the development of semiconductor devices provided with thin film transistors (TFTs) and thin film diodes (TFDs) that are formed on the same substrate, and development of electronic equipment having such semiconductor devices.
For example, Patent Document 1 discloses an image sensor provided with an optical sensor portion that uses TFDs and driving circuits that use TFTs, provided on the same substrate. In the method for manufacturing in Patent Document 1, TFTs and TFDs are manufactured using a crystalline semiconductor film that is obtained through performing a heat treatment after adding a catalyst element to an amorphous semiconductor film that is formed on a glass substrate.
However, in the method set forth in Patent Document 1, it has been difficult to optimize the crystalline states for the individual semiconductor layers for the TFTs and the TFDs.
Given this, Patent Document 2 discloses a method for optimizing by controlling separately the crystalline states of the semiconductor layers of the TFTs and the TFDs that are formed by crystallizing the same amorphous semiconductor film. The technology set forth in Patent Document 2 uses a laser crystallizing method to cause a higher level of crystallinity in the TFD semiconductor layer than the crystallinity in the TFT semiconductor layer. In the manufacturing method set forth in Patent Document 2, the crystalline semiconductor film, having optimal crystallinity as a TFT semiconductor layer, is irradiated with a laser beam to cause melting and recrystallization, to obtain a crystalline semiconductor film having greater crystallinity, as the semiconductor layer for the TFDs. Patent Document 2 discloses the average surface roughness (Ra) of the TFD semiconductor layer, which has undergone the melting and recrystallization, as being greater than the average surface roughness of the TFT semiconductor layer. The crystalline semiconductor film that is used as the TFT semiconductor layer is formed through crystallizing an amorphous semiconductor film through a method that uses a catalyst element, in the same way as in Patent Document 1, or through a method of irradiation with a laser beam.